In reactivating a HP87XM I am trying to restart a HP9121 dual 3 1/2 inch floppy drive and now find that this was the first application of the Sony 3 1/2 inch drive so the floppys were only formatted for 270 kilobytes. By experiment I have determined that the HP87XM and HP9121 will not initialize either the low density 3 1/2 floppys or any higher density. I have put in an ad for 3 1/2 inch 270KB floppys but have not had, perhaps not suprisingly, a single response.
By open case inspection, a low density 3 1/2 inch floppy seems to enter the drive freely, engage and spin OK so the problem seems to be entirely related to magnetic preprogramming to allow the disc to accept the initialize command.
Any feedback, particularly from current users of the HP9121, certainly would be appreciated.